This invention relates to an improved container extraction and transfer mechanism for automated storage and retrieval systems, and more particularly to an extraction and transfer mechanism designed for extraction of handleless modular containers from a first selected location in a storage matrix and transfer in either lateral direction into a second selected storage location.
The environment in which the present invention is intended to operate is well-known and has been the subject of many patents, two of these being shown in U.S. Pat. Nos. 3,526,326 and 3,883,008, both being in the name of John A. Castaldi and both being assigned to the present assignee. The foregoing patents depict automated storage and retrieval systems having in common at least one matrix of storage locations for modular removable containers, tote boxes, or bins, a stacker crane assembly, which moves horizontally along an aisle in front of or between storage locations, a vertically movable platform on the stacker crane assembly, and suitable motors, position sensors, limit switches, and a selected control system to enable positioning the platform at a suitable x-y coordinate address representing a selected storage location in the storage matrix. The foregoing type of automated storage and retrieval system is known and the description relating to it as described in the foregoing Castaldi patents is incorporated herein by reference.
The present invention concerns an improved extraction and transfer mechanism which is mounted on the stacker crane platform and which will handle container extraction and transfer, once the platform is positioned at a selected location in the storage matrix.
Various types of extraction devices have been proposed in the art. The foregoing Castaldi U.S. Pat. No. 3,526,326 utilized a magnetic extractor to engage a magnetic plate attached to the end of each bin or container. This is adaptable to very light containers, and because of the space occupied by the magnet assembly on the platform, it is suitable only for extraction and subsequent replacement back in the same lateral direction from which the container was extracted.
Castaldi U.S. Pat. No. 3,883,008 illustrates a hook extractor adapted to cooperate with a special handle on the end of the container, by rotating a hook into an upright position inside the inverted L-shaped recess in the handle. The extracted container is removed onto a pair of endless belts which support the container and reduce the strain upon the hook. The success of this type of extraction system depends upon precise positioning of the handles of the modular containers residing throughout the matrix and misalignment of a particular container may result in faulty engagement of the system.
Another type of extraction system involves insertion of a lifter platform beneath a container, lifting and withdrawing it, as exemplified in U.S. Pat. No. 3,934,741 to Wentz. This system results in much lost space in the storage matrix, since vertical spacing between container supports must be provided to allow insertion of the lift or shuttle platform.
Other types of extraction mechanisms for automated storage and retrieval systems of the type described use a single pin extractor as shown and described in U.S. Pat. No. 4,556,355 issued to Michael Glater and assigned to the present assignee. Another extractor using two continuous belts, each with a single pin is shown in U.S. Pat. No. 4,361,411 to Di Liddo. Still another type of extraction mechanism using a pair of continuous loops, each with a radially inner and outer pin spaced along it is shown in U.S. Pat. No. 4,352,622 to Wieschel. These bilateral extraction systems are an improvement over the previously described systems, since they enable extraction and then transfer in either lateral direction once the container is extracted, i.e., providing for bilateral insertion of the container into the storage matrix on either side of the aisle. However, the foregoing systems still require special handles on the modular containers which must be precisely positioned in the matrix for engagement by the hooks of the extraction mechanism. And since the handles protrude on each end of a container, they reduce the usable storage space.
An extraction system for containers in sloped storage locations is shown in U.S. Pat. No. 4,563,120, which uses a lug on a continuous loop belt to engage a recess on the bottom of a handless container.
A system for extending arms with gripper pads for gripping the sides of handless tote boxes is shown in U.S. Pat. No. 4,492,504 to Hainsworth.
One proposal has been made in a commercially-available device for an automated storage and retrieval system which employs a pair of continuous loop chains with gripper pads for frictionally engaging the sides of a handleless container to extract the container from a storage matrix. Should the pad-type gripper in this commercially-available design become disengaged during an extraction cycle, it cannot re-engage itself without manual intervention, and reliance solely on the gripper for movement of the container could produce wear. Also for a "cross over," i.e., extraction from one lateral side and transfer to the other lateral side of the platform, the described mechanism must release, cycle to the other end of the container, re-engage and then insert the container on the other side.
Accordingly, one object of the present invention is to provide an improved extraction and transfer mechanism for an automated storage and retrieval system.
Another object of the invention is to provide an extraction and transfer mechanism for container extraction and replacement in a storage matrix, which has greater reliability and which increases usable storage space.
Another object of the invention is to provide an improved extraction and transfer mechanism for extraction and bilateral transfer of handleless containers among storage locations without need for repositioning or re-engaging the container when it is on the platform of a stacker crane.